The Added Value in Accessible ePub3
Some examples of the immense added value in Accessible ePub3 as a format choice
| Feature | ePub2 @ $.50/page | ePub3 @ $.80/page | Accessible ePub3 @ $.90/page |
| Semantic Structure | Limited semantic structure support, primarily based on basic HTML without ARIA roles or advanced tags. | Relies on standard HTML semantics. | Emphasizes proper semantic tagging, such as headings, lists, tables, etc., to enhance accessibility. |
| Navigation | Simple linear navigation with a basic table of contents; lacks landmarks or structural divisions. | Basic linear reading order and basic navigation elements (e.g., TOC). | Improved navigation with landmarks, page lists, and navigation tables for easier content navigation by assistive technologies. |
| Image Descriptions | Basic support for image alt text, but often lacks comprehensive image description requirements. | Alt text for images can be provided, but it may be limited or missing. | Requires comprehensive and accurate image descriptions (alt text) to provide context and information for non-text content. |
| Tables | Supports simple tables in HTML, but complex tables are often represented as images | Standard HTML tables can be used. | Requires proper table markup, including table headers and captions, to improve accessibility for screen readers. |
| Forms | Not supported; ePub2 doesn’t include form fields or interactive form capabilities | Standard HTML form elements. | Requires well-structured forms with properly associated labels and instructions. |
| MathML | No native MathML support; mathematical expressions are typically rendered as images | Supported but not always utilized. | Encourages the use of MathML for mathematical equations and formulas. |
| ARIA | Because the ePub2 specification does not include ARIA attributes, it lacks enhanced accessibility features such as roles, states, and properties that assistive technologies rely on to interpret complex content. This is a significant limitation compared to ePub3 and Accessible ePub3, where ARIA is used to improve navigation and content comprehension for users with disabilities. | Limited use of ARIA attributes. | Utilizes ARIA attributes for improved accessibility, like ARIA landmarks and roles. |
| Text-to-Speech (TTS) Support | Basic TTS functionality is available if the reading software or device supports it, but ePub2 does not inherently include advanced TTS features | Basic TTS functionality is available. | Enhanced TTS support with better synchronization and handling of reading order. |
| Text Resize | Text resizing is a core feature in ePub2, allowing readers to adjust font size based on their preferences | May or may not support dynamic text resizing. | Supports dynamic text resizing without loss of content or functionality. |
| Language and Spelling Assistance | Lacks advanced language tagging for specific phrases or sections and does not support embedded spelling assistance. Spell-checking and language support depend entirely on the capabilities of the reading software rather than the ePub2 format itself. | Relies on external tools and browser support. | Provides built-in language and spelling assistance features. |
| Media Overlays (audiobooks) | Not supported; lacks synchronized audio and text capabilities. | Supported through external applications. | Incorporates built-in support for media overlays, making audiobooks more accessible. |
| Metadata for Accessibility | Accessibility metadata is minimal or absent, making it harder to identify accessibility features | Limited focus on accessibility metadata. | Extends metadata support to provide specific accessibility information, like text-to-speech settings and accessibility features. |
| Reading Order Control | Lacks advanced control mechanisms, such as landmarks and structural divisions, | Reading order may not be explicitly defined. | Allows for explicit reading order control through proper markup and techniques. |
| Text Adaptation | Lacks more advanced adaptation features found in newer formats, such as dynamic layout adjustments based on content type (e.g., tables vs. paragraphs), media queries, or adaptive styling based on reader preferences. Customization beyond font size is mostly dependent on the e-reader's capabilities | Limited control over text presentation. | Allows users to adapt text presentation to suit their needs (e.g., change font, size, color). |
| Text-to-Speech (TTS) Control | Lacks advanced tags or attributes to fine-tune the TTS experience | Basic control over TTS settings, if supported by the reading system. | Provides better control over TTS settings, like voice selection and speed. |
| Multimedia Support | ePub2 does not natively support audio and video elements. Multimedia integration typically requires embedding external links or relying on third-party plugins within the reading software, which can result in inconsistent user experiences | Allows embedding of audio, video, and interactive elements. | Encourages providing alternatives and ensuring compatibility with assistive technologies. |
| Scripting | No or limited scripting support, resulting in less dynamic and interactive content. | Supports JavaScript for creating interactive and dynamic content. | Encourages using scripting responsibly, ensuring accessibility is not compromised. |
| Standards Compliance | Fails to meet modern accessibility standards such as WCAG (Web Content Accessibility Guidelines) and lacks support for ARIA roles and semantic HTML5 elements, which are incorporated in ePub3. Consequently, ePub2 may fall short in accessibility and multimedia compatibility compared to more recent digital publishing standards | Complies with EPUB3 standard. | Aligns with accessibility standards like WCAG, aiming for broader compliance. |
| Certification Initiatives | The ePub2 standard was not developed with formal certification programs to validate accessibility, interoperability, or compliance with modern publishing standards. Unlike Accessible ePub3, which aligns with certification initiatives such as those by the DAISY Consortium to ensure accessibility, ePub2 lacks mechanisms for certifying compliance with accessibility or usability benchmarks | No specific certification initiatives. | Organizations like Benetech Global Certified Accessible (GCA) may offer certification programs (e.g., Global Certified Accessible Program). |
| Ongoing Development | The ePub2 standard is considered legacy and has not been updated since the release of ePub3. Development focus has shifted entirely to ePub3 and newer formats, which continue to evolve to meet modern standards for accessibility, multimedia, and interactivity. As a result, ePub2 lacks support for newer features and is unlikely to receive future enhancements, making it less adaptable to current digital publishing needs | EPUB3 standard development continues. | Accessibility features may be refined based on evolving standards and user needs. |
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